The synthesis of chiral carbene ligands derived from bis(tetrahydroisoquinoline) bearing sterically highly demanding, rigid substituents is described. Their corresponding gold complexes were structurally elucidated and successfully employed as catalysts for the desymmetrization of 1,4-diynamides.
Gold-Catalyzed<i>endo</i>-Cyclizations of 1,4-Diynes to Seven-Membered Ring Heterocycles
endo‐Rule for gold: A highly endo‐selective gold‐catalyzed cycloisomerization of 1,4‐diynes was developed. By employing electron‐rich phosphines and N‐heterocyclic carbenes as ligands, a number of 1,4‐diynes could be cyclized in a desymmetrizing fashion to form dihydrodioxepines and enantiomerically enriched tetrahydrooxazepines (see scheme).